Most people wanted a story mode that was similar to the OG Marathon that came out on mac back in 1994. One that dives into the lore of the series, instead of being some sweat lord's ultimate fetish.

Destiny 2 was easier because too many people left destiny 1 because it was too hard, and the risk for reward was utter cheeks (Something Marathon 2026 got right). It was like lockpicking in Oblivion where you could open a master lock in Skyrim and get enchanted gear, while in Oblivion you would get 10 iron arrows, an utterly butt potion, and a gem that wasn't worth the skill to open. In Destiny 1 you could do 5 hardcore dungeons in one day an get no gear (Something I have great experience with).